Peel and wash the carrots and cut them into small cubes. Cook in boiling salted water for about 3 minutes, drain and drain. Wash, clean, quarter and seed the tomatoes. Cut the flesh into small cubes. Mix vegetables.
Strip rosemary needles from the stems. Peel and finely dice onion. Melt the fat. Fry rosemary and diced onion in it. Add flour and sweat. Add stock and cream while stirring constantly, bring to the boil. Season to taste with salt and pepper. Cut mozzarella into thin slices. Spread the casserole dish with olive oil. Layer sauce, Maultaschen and diced vegetables.
Season to taste with salt and pepper. Cut mozzarella into thin slices. Spread the casserole dish with olive oil. Layer sauce, Maultaschen and diced vegetables. Cover with mozzarella. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for about 40 minutes. Serve garnished with rosemary